It’s difficult to tell, but I understand she’s quite short (height) and seems very slim - with quite a big projection. I also understand she’s augmented, or has had implants.
She definitely has a small back, so possibly around 30-32 and I’d be thinking she’s around KK or bigger - but it could be a custom bra.
I’ve attached what a 32KK looks like. And she’s definitely bigger than that. So possibly L.